From: Benjamin LaHaise <bcrl@kvack.org>
To: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org
Subject: bdi has dirty inode after umount of ext4 fs in 3.4.83
Date: Fri, 21 Mar 2014 11:25:41 -0400 [thread overview]
Message-ID: <20140321152541.GA23173@kvack.org> (raw)
Hello Al and folks,
After adding some debugging code in an application to check for dirty
buffers on a bdi after umount, I'm seeing instances where b_dirty has
exactly 1 dirty inode listed on a 3.4.83 kernel after umount() of a
filesystem. Roughly what the application does is to umount an ext3
filesystem (using the ext4 codebase), perform an fsync() of the block
device, then check the bdi stats in /sys/kernel/debug/252:4/stats (this
is a dm partition on top of a dm multipath device for an FC LUN). I've
found that if I add a sync() call instead of the fsync(), the b_dirty
count usually drops to 0, but not always. I've added some debugging
code to the bdi stats dump, and the inode on the b_dirty list shows up as:
inode=ffff88081beaada0, i_ino=0, i_nlink=1 i_sb=ffff88083c03e400
i_state=0x00000004 i_data.nrpages=4 i_count=3
i_sb->s_dev=0x00000002
The fact that the inode number is 0 looks very odd.
Testing the application on top of a newer kernel is a bit of a challenge
as other parts of the system have yet to be forward ported from the 3.4
kernel, but I'll try to come up with a test case that shows the issue.
In the meantime, is anyone aware of any umount()/sync related issues that
might be affecting ext4 in 3.4.83? Thanks in advance for any ideas on
how to track this down. Cheers,
-ben
--
"Thought is the essence of where you are now."
next reply other threads:[~2014-03-21 15:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-21 15:25 Benjamin LaHaise [this message]
2014-03-23 13:14 ` bdi has dirty inode after umount of ext4 fs in 3.4.83 Jan Kara
2014-03-25 22:09 ` Benjamin LaHaise
2014-03-26 5:32 ` Jan Kara
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